The present invention relates to a golf club head and a method of manufacturing the golf club head.
From the viewpoints of stabilizing the quality and making it easy to procure the material, instead of natural wood such as persimmon or cherry, titanium alloy or aluminum alloy is formed into a hollow external shell, or a core (filling member) made of foaming synthetic resin is covered with a fiber reinforced resin layer such as a carbon fiber reinforced resin layer or a glass fiber reinforced resin layer, to manufacture a head main body of a golf club head referred to as a wood, which will be referred to as a "head" in this specification hereinafter. Golf clubs made in the above manner are widely put into practical use recently.
Further, there is a tendency that a face plate made of fiber reinforced resin or metal is attached onto a face of the head body in order to extend the flying distance of a ball, or a sole plate made of metal, the specific gravity of which is higher than that of the head body, is attached to the sole portion of the head in order to adjust the weight so that a position of the center of gravity is lowered.
Conventionally, the sole plate or face plate is fixed to the head body by means of screws or adhesive. Also, in the case of a face plate, it is engaged with and fixed to a recess provided on the face portion. Accordingly, there is a possibility that the screws and engaging portions are unfastened or the adhesive is peeled off by the action of vibration caused when the golf club is used.
Recently, the following head and manufacturing method thereof are disclosed in Japanese Unexamined Patent Publication No. 62-207474.
As illustrated in FIG. 8, a face plate 3 is attached onto a surface of a fusible core 1, and the fusible core 1 with the face plate 3 is accommodated in a mold 5 composed of a plurality of blocks 5a, 5b, 5c. Metallic material is then poured into a cavity 8 from a pouring gate 7 so as to conduct pressure casting. Then the core 1 is removed by drilling chaplets 9 supporting the core 1. In this way, the head 13 is provided, in which the face plate 3 is attached onto the face 12 of the head body 11 as illustrated in FIG. 9.
However, even if the face plate 3 is retained onto the face 12 by the internal-chill casting process when the head body 11 is cast, since the face plate 3 has no means for engaging with the head body 11, there is a possibility that the face plate 3 is peeled off from the head body 11 by the vibration caused in the use of a golf club, and the face plate 3 is disconnected from the face 12.
Different from attaching the face plate and sole plate, Japanese Unexamined Patent Publication No. 2-206481 or Japanese Patent Publication No. 6-7876 discloses a head and a manufacturing method thereof in which a weight adjusting member is embedded in an iron head body during the casting process of the head.
FIG. 10 is a view showing a mold used for the method of manufacturing a head disclosed in Japanese Unexamined Patent Publication No. 2-206481. On a mating surface of the split type mold 14, there are provided recess portions 17, 18 communicated with the cavity 15 for receiving and holding base portions of the support pins 19.
While the weight adjusting member 21 is held by the support pins 19 in the cavity 15 as illustrated in the drawing, molten metal is poured from the pouring gate 23 into the cavity 15. In this way, a head is manufactured by casting so that the weight adjusting member 21 is included in the main body of the head.
However, when this method is applied to a case in which the face plate is attached to the main body, a hole formed as a result of removal of the support pin 19 is left, which requires troublesome after-treatment. Even when the method illustrated in FIG. 8 is adopted, troublesome after-treatment is required for the holes 25 shown in FIG. 9 which are formed to remove the core 1.
Further, Japanese Patent Publication No. 6-7876 discloses a head 37 and a manufacturing method thereof illustrated in FIGS. 11 and 12, in which a substantially U-shaped weight adjusting member 29 made of material, the melting point of which is different from that of the head body 27, and the specific gravity of which is higher than that of the head body 27, is arranged in the head body 27, and while extending portions 33 provided at both large weight portions 31 are exposed onto the heel and toe sides of the back portion 35 of the head body 27, the parts are subjected to casting so as to be fixed at predetermined positions in the head 37.
However, this method is disadvantageous in that the weight adjusting member 29 is supported only by the back portion 35 in the manner of cantilever, so that the weight adjusting member 29 is inclined and shifted from a predetermined position in the process of casting.